Introduction

Key plants are those specific plant species or cultivars that may be infested with key insect or mite pests’ problems every year. This can vary from location to location and from year to year. Often, certain cultivars may be more susceptible than others. Here is a list that I gathered from references listed at the end of this article plus personal observations when visiting commercial greenhouses. It is helpful to develop your own list based upon your own experience and observations. The target audience of this factsheet is commercial greenhouse and herbaceous perennial growers.

Key insect and mite pests include aphids, broad mites, citrus mealybugs, cyclamen mites, fungus gnats, two-spotted spider mites, whiteflies, and western flower thrips.

Aphids

Key bedding plants affected: Ageratum, alyssum, basil, begonia, calibrachoa, Cole crops, celosia, chrysanthemum, dahlia, dianthus, eggplant, geraniums (ivy and zonal), gerbera daisy, herbs (many), fuchsia, garden impatiens, Ipomoea, leafy greens, marigolds, nasturtium, pansy, pepper, portulaca, primula, salvia, snapdragon, tomato, verbena, zinnia, etc.

Key herbaceous perennials affected: Acanthus, Achillea, Alcea, Asclepias, Aster, Bellis, Dianthus, Digitalis, Heuchera, Helianthus, Helleborus, Hibiscus, Monarda, Papaver, Oleander, Phlox, Primula, Rudbeckia, Salvia, Sedum, Sempervivum, Veronica, and Viola .

Root Aphids:

Aster, Coreopsis, Lysimachia, Sedum, Semperviven, Veronica.

Broad Mites

Key bedding plants affected: Ageratum, begonia, chrysanthemum, dahlia, fuchsia, gerbera daisy, English ivy, New Guinea impatiens, salvia, scaevola, snapdragon, verbena, vegetative petunia, peppers, Thunbergia, torenia and zinnia.

Citrus Mealybugs

Key bedding plants affected: Begonia, chrysanthemum, coleus, English ivy, English primrose, gerbera daisy, fuchsia, gardenia, and hibiscus. (Many tropical foliage plants and house plants are susceptible to long tailed mealybugs).

Cyclamen Mites

Key bedding plants affected: Ageratum, begonia, celosia, chrysanthemum, dahlia, fuchsia, gerbera daisy, rosemary, petunia, impatiens, English ivy, geranium, Ipomoea, snapdragon, verbena, Viola, and zinnia.

Key herbaceous perennials affected: Aconitum, Clematis, and Delphinium.

Fungus Gnats

Wide host range, most common in damp areas. Young plant more susceptible than mature plants.

Key plants affected: Plants with succulent stems including geranium, coleus, poinsettia, and sedum.

Two-spotted spider mites

Key bedding plants affected: Ageratum, beans, celosia, dahlia, dracaena (spike), eggplant, English ivy, fuchsia, gerbera daisy, geraniums (especially ivy), gomphrena, herbs (many especially lemon balm, lemon verbena, etc.), hibiscus, Ipomoea, impatiens, lantana, lobelia, marigolds, New Guinea impatiens, portulaca, primrose, salvia, scaevola, Thunbergia, tomatoes, verbena, and vinca vine.

Key herbaceous perennials affected: Alcea, Aquilegia, Baptisia, Buddleia, Campanula, Delphinium, Filipendula, Gaillardia, Hemerocallis, Hydrangea, Iris, Lamium, Lavatera, Monarda, Nepeta, Papaver, Phlox, Potentilla, Primula, Rudbeckia, Scabiosa, Thalictrum, Verbena, and Viola.

Whiteflies - Greenhouse Whiteflies

Key bedding plants affected: Ageratum, alyssum, begonia, bacopa, calendula, chrysanthemum, fuchsia, gerbera daisy, herbs (many such as scented geraniums, and lemon verbena), lantana, primula, salvia, tomato, verbena, and zinnia.

Key herbaceous perennials affected: Acanthus, Aster, Alcea, Hibicus, Helenium, Leonotis, Lavatera, Malva, Primula and Solidago. Whiteflies are generally more of an issue if plants have been overwintered from season to season.

Whiteflies - Sweetpotato Whiteflies Primarily on poinsettia crops, also gerbera daisy, hibiscus.

Key herbaceous perennials affected: Asters, Gaillardia, Eupatorium, Helianthus, Lavandula, and Salvia.

Western Flower Thrips

Key Bedding Plants Affected: Ageratum, alyssum, basil, bacopa, begonia, calibrachoa, calendula, celosia, chrysanthemum, dahlia, dianthus, dracaena spikes, eggplant, fuchsia, herbs (many especially tarragon), gazania, geraniums (ivy), gerbera daisy, Ipomoea, marigolds, New Guinea Impatiens, petunia, pepper, portulaca, primula, salvia, snapdragon, tomato, verbena, and zinnia.

Key herbaceous perennials affected: Alcea, Asclepias, Aster, Campanula, Centurea, Chrysanthemum, Coreopsis, Crocosmia, Digitalis, Echinacea, Eupatorium, Lamium, Lupinus, Malva, Monarda, Penstemon, Platycodon, Polemonium, Phlox, Rudbeckia, and Tanacetum.

Echinothrips americanus (poinsettia thrips) – many different tropical plants

 

---

Disclaimer for Fact Sheets: The information in this document is for educational purposes only. The recommendations contained are based on the best available knowledge at the time of publication. Any reference commercial products, trade or brand names is for information only, and no endorsement or approval is intended. UConn Extension does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available. The University of Connecticut, UConn Extension, College of Agriculture, Health and Natural Resources is an equal opportunity program provider and employer.

Resources

• Baker, J. R. 1994. Insect and Related Pests of Flowers and Foliage Plants. North Carolina Cooperative Extension Service, North Carolina State University AG-136, Raleigh, NC. https://content.ces.ncsu.edu/insect-and-related-pestsof-flowers-andfoliage-plants
• Chase, A.R., M.L. Daughtrey, and R. A. Cloyd. 2018. Compendium of Bedding Plant Diseases and Pests. The American Phytopathological Society. (APS). St. Paul, Minn. 170 pp.
• Cranshaw, W. and D. Shetlar. 2018. Garden Insects of North America: The Ultimate Guide to Backyard Bugs. 2nd edition. Princeton University Press. 704 pp.
• Casey, C. Ed. 1997. Integrated Pest Management for Bedding Plants. A Scouting and Pest Management Guide. Cornell Cooperative Extension Publication No. 407. 109 pp.
• Gill, S., and J. Sanderson. 1998. Ball identification guide to greenhouse pests and beneficials. Ball Publishing. Batavia, IL. 244 pp.
• Gill, S. R. A. Cloyd, J. R. Baker, D. L. Clement, and E. Dutky. 2006. Pests and Diseases of Herbaceous Perennials: The Biological Approach. Ball Publishing. Batavia, IL. 422 pp.
• Lindberg, H. 2017. Attention Scouts: Crops that are Insect Magnets in the Greenhouse. Michigan State Extension.